1. Field
This invention relates to energy storage devices, particularly to printed energy storage devices.
2. Description of the Related Art
Thin and flexible energy storage devices are needed for powering thin and/or small electronic devices in the consumer market. For example, lights and sound in greeting cards, thin advertisement tools like magazine inserts, skin care products, safe pass cards, some miniature medical devices, etc. can be powered by using thin batteries. Some thin batteries already exist on the market (e.g., zinc carbon batteries produced by Enfucell Oy Ltd. of Vantaa, Finland and Blue Spark Technologies, Inc. of Westlake, Ohio, and lithium polymer batteries produced by Solicore, Inc. of Lakeland, Fla.). These batteries generally have a thickness from about 0.45-0.7 mm. They are sealed in a pouch unit cells with two poles for wired connection to devices which need power.
Zinc-manganese dioxide (Zn/MnO2) batteries are primary batteries (e.g., one time use). These batteries can be filled with an aqueous solution of zinc and ammonia salts or potassium hydroxide. They have an initial voltage of 1.5-1.6V and are designed for low or moderate current drain. Shelf life of these batteries is 1-3 years. Main advantages of Zn/MnO2 batteries are cost and safety. They are the most affordable batteries on the market due to cheap and abundant raw materials for the battery build. These materials are considered “green” due to non-toxicity.